Such electric machines are required for a wide variety of drive tasks, and generate heat losses during the operation thereof due to electrical losses such as eddy-current losses or copper losses. In electric machines, one power-limiting factor is the quality of the dissipation of the generated heat losses. In particular in the case of designs in which parts subjected to high temperatures within the electric machine are not directly cooled by a cooling medium, utilization of an active mass that is used is under some circumstances not optimal. Special zones in which a dissipation of heat within an electric machine may be problematic are in particular stator winding heads and a rotor of the electric machine.
It is known for electric machines to be cooled using a gaseous or liquid medium. Air is typically used as gaseous medium, and water is typically used as liquid medium, where, in the case of liquid-type cooling, electric machines are normally cooled by a cooling jacket. Electric machines may furthermore be self-cooled or externally cooled.